Dias F.C.,Task Group for the Extension of the Continental Shelf EMEPC |
Gomes-Pereira J.,Task Group for the Extension of the Continental Shelf EMEPC |
Gomes-Pereira J.,University of The Azores |
Tojeira I.,Task Group for the Extension of the Continental Shelf EMEPC |
And 5 more authors.
PLoS ONE | Year: 2015
Estimating the area of seabed surfaces from pictures or videos is an important problem in seafloor surveys. This task is complex to achieve with moving platforms such as submersibles, towed or remotely operated vehicles (ROV), where the recording camera is typically not static and provides an oblique view of the seafloor. A new method for obtaining seabed surface area estimates is presented here, using the classical set up of two laser devices fixed to the ROV frame projecting two parallel lines over the seabed. By combining lengths measured directly from the image containing the laser lines, the area of seabed surfaces is estimated, as well as the camera's distance to the seabed, pan and tilt angles. The only parameters required are the distance between the parallel laser lines and the camera's horizontal and vertical angles of view. The method was validated with a controlled in situ experiment using a deep-sea ROV, yielding an area estimate error of 1.5%. Further applications and generalizations of the method are discussed, with emphasis on deep-sea applications. © 2015 Dias et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Calado A.,Task Group for the Extension of the Continental Shelf EMEPC |
Afonso A.,Task Group for the Extension of the Continental Shelf EMEPC |
Lourenco N.,Task Group for the Extension of the Continental Shelf EMEPC |
Abreu M.,Ministry of Agriculture
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2012
The ROV LUSO, a 6000m rated work class ROV which supports a large range of multidisciplinary research activities on the deep ocean become operational in 2007, by the Portuguese Task Group for the Extension of the Continental Shelf. Here, we report on the LUSO project background, its characteristics and perform a three year appraisal, LUSO seagoing operations, operational performance and team building efforts. So far, ROV LUSO operated in three scientific campaigns (2008-2010), targeting the Azores Platform, southern Azores seamounts, the Mid-Atlantic Ridge, and the Selvagens Islands at Madeira Archipelago. Overall, 80 LUSO dives were accomplished, corresponding to a total of 320 hours of submarine operations. Since early 2011 EMEPC has a new facility for the ROV and other marine equipment maintenance, repair and development. This infrastructure is also used as an in-house training center and the logistics base of all the maritime operations. It will enable the implementation of LUSO development plans (2012-2015) which comprise, developing task specific skids (e.g. geological and fluid sampling), fitting an electromagnetic survey system, a vibracorer system, a 3D camera and integrating Video annotation system in LUSO video record infrastructure.
Gomes-Pereira J.N.,University of The Azores |
Gomes-Pereira J.N.,Task Group for the Extension of the Continental Shelf EMEPC |
Tempera F.,University of The Azores
Marine Biodiversity | Year: 2015
Nemertesia ramosa (Lamarck, 1816) is a large eurybathic hydrozoan species. Its habitat and spatial distribution in the Azores archipelago (central North Atlantic) are described based on 22 new records collected in situ by scuba diving and by observations using a drop-down camera and remote operated vehicles (ROVs) between 2004 and 2011. N. ramosa grows on hard substrates in mono and multi-specific assemblages. In the Azores it is well known in the sublittoral at 15–158 m depth in the central group of islands, but historical records exist from seamounts down to bathyal grounds of nearly 1000 m. Scuba diving surveys generally reveal N. ramosa as an occasionally occurring and rare species in the infralittoral (1–9 colonies 10−3 m−2), although it may also be common and even abundant at some sites. A circalittoral aggregation was assessed in detail exhibiting densities of up to 2.82 colonies m−2 on rocky substrate and one order of magnitude lower on mixed bottom (0.25–0.55 colonies m−2). An aggregated spatial distribution is described, with aggregations being considered hydroid gardens (>1–9 10−1 m−2). Colonies measured on ROV imagery averaged 23.5 cm in height (STD = 4.1). Taller colonies (max = 36.7 cm) were registered on rocky outcrops protruding more than 15 cm. N. ramosa co-occurred mainly with brown and red algae, bryozoans, polychaetes, and other hydroids. A diverse ichthyofauna was associated to these habitats. Circalittoral communities of N. ramosa included hydrozoans, sponges, and fish. © 2015 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg